@Kei ***
book directly in their site. Ana.com Koreanair.com.
I found their prices in main website same or cheaper than 3rd party. ANA typically has one flight a day deep discount in their site. Btw I don't recommend exit seats. Yes a little more leg room, but it's right next to bathrooms and steward galley. Didn't sleep at all in my flight that I choose these seats. Lesson learned for me.